Plastic containers



Dec. 3, 1968 R. A. TIGNER 3,414,180

PLASTIC CONTAINERS Original Filed March 14, 1963 2 Sheets-Sheet 1 I NVENTOR. Rub an A 779/; er

1968 R. A, TIGNER 5, 0

PLASTIC CONTAINERS Original Filed March 14, 1963 2 Sheets-Sheet zINVENTOR. Rube/7 H. T/gne/ ATTORNEY United States Patent 3,414,180PLASTIC CONTAINERS Ruben A. Tigner, Pinconning, Mich, assignor to TheDow Chemical Company, Midland, Mich., a corporation of Delaware Originalapplication Mar. 14, 1963, Ser. No. 265,219, now Patent No. 3,338,997,dated Aug. 29, 1967. Divided and this application Jan. 9, 1967, Ser. No.641,065

2 Claims. (Cl. 229-15) ABSTRACT OF THE DISCLOSURE A plastic foamcontainer having a raised bottom and a lower peripheral leg. Areinforcing gusset is formed integrally with and between the lowerperipheral leg and the raised bottom, the gusset being expanded to asubstantially greater extent than the adjoining portions of the cup toprovide such reinforcement.

This application is a division of application Ser. No. 265,219, filedMar. 14, 1963, and now issued as U.S. Patent No. 3,338,997.

This invention relates generally to plastic containers with raisedbottoms and bead-like lips and, more particularly, relates to plasticfoam containers with features especially adapted for vending machines.

While in the past it has been relatively simple to form plastic filmcontainers with raised bottoms for purposes of rigidity, stacking andappearance, such simplicity of forming has not been present with plasticfoam containers, such as cups, because of uneven flow and otherunpredictable characteristics of foam. Since in the past it has beendifficult to control side wall thickness of foam by an economical,vacuum forming technique, such cups previously have been generallyavoided in vending machine use. Because of the prior necessity ofemploying matched dies to have some degree of control in forming fromfoam sheets and, further, because of the reverse pitch required forstacking shoulders in raised bottom cups which has been unobtainable inmatched die forming, raised bottom foam cups previously have beenimpractical to manufacture by this method also. The novel vacuum formingplug die technique of this invention has eliminated thatimpracticability.

In addition, in the prior conventional method of forming containers fromnonexpanded plastic sheet, the bottom could only be formed after thesheet had been drawn into the bottom of the forming mold while, in thepresent invention, the bottom of the container can be formed first inthe forming cycle or at any later time to gain the desired bottomcharacteristics. Any other physically acceptable technique, such as byfoaming in place or by injectionmolding, has proven to be too expensiveto be practical, the relative cost thereof being approximately ten timesas great as that for producing expanded plastic containers according tothe techniques of the present invention. Furthermore, prior teachingshave not been able to providing for an efficient and effective enoughbeadlike lip on plastic foam containers to render them practical forvending machine operation.

Accordingly, it is an object of the present invention to provide foamedplastic containers which are economically feasible and readily adaptablefor vending machine operation.

3,414,180 Patented Dec. 3, 1968 Another object of the present inventionis to provide a novel form of raised bottom container adapted forefficient stacking and release.

Yet another object of the present invention is to provide a plastic foamcontainer with an even wall and a desired bottom thickness, whilemaintaining an economical density.

A further object of the present invention is to provide for plastic foamcontainers which include a raised bottom and a bead-like lip forefiicient vending machine operation.

Brieflly then, the present invention comprehends a novel raised bottomplastic container with a bead-like lip. The side 'walls of the containerare inclined and extended beyond the actual bottom of the container suchthat the diameter of the periphery of the extension is less than that ofthe actual bottom thereof to provide for releasable nesting of aplurality of such containers within one another. Apparatus of thisinvention forms the above bottom configuration prior to completion ofthe forming of the side wall, employing single and double vacuum drawingin novel dies to provide a controlled bottom weight and thickness. Theapparatus also provides for controlled side wall thickness. A crushingand vacuum technique for forming a desirable bead-like lip while thecontainer is in its forming die is additionally provided.

Yet additional objects and advantages of the present invention, and itsnumerous cognate benefits and features are even more apparent andmanifest in and by the ensuing description and specification taken inconjunction with the accompanying drawing in which, wheresoeverpossible, like characters of reference designate corresponding materialand parts throughout the several views thereof, in which:

FIGURE 1 is an elevational view of a foamed plastic cup formed accordingto the principles of the present invention;

FIGURE 2 is a top view thereof;

FIGURE 3 is a bottom view thereof;

FIGURE 4 is a cross-sectional view of a plurality of cups like that ofFI 1, in a stacked relationship, with the cross-section of each cupbeing as if taken along the reference line 4-4 of FIG. 1;

FIGURE 5 is a cross-sectional view of assembled apparatus of the presentinvention prior to the forming of a cup;

FIGURE 6 is a view similar to FIG. 5 only showing the apparatus in asubsequent step of forming the bottom wall of the cup;

FIGURE 7 is still another view like FIG. 5 only showing a subsequentstep, to that shown in FIG. 6, of forming the side wall of the cup; and

FIGURE 8 is yet another view like FIG. 5 only showing a final step offorming a bead-like lip for the cup.

Referring now more particularly to FIGS. 1 to 4, container 10 is shown,in an exemplary form, as a frustoconically shaped cup preferably formedof a plastic foam, such as expanded polystyrene, it being understoodthat such containers can be formed of other adaptable foam or plasticfilm materials if so desired.

Since container 10 is particularly adapted for automatic vending machinedispensing, it includes, at the upper periphery of its side wall 12, abead-like lip 14 for engagement by fingers of a vending apparatus.

Container 10 also includes a raised bottom 16 extending somewhatinwardly from the bottom periphery of the container formed by thecircular foot 18 such that the diameter, or other configuration if foot18 is other than circular, is concentric with and smaller than thediameter or other configuration of botom 16. This permits stacking ofone container within the other, that is, the foot of an upper containerresting upon the bottom of the next lower container, as illustrated inFIG. 4.

If container is formed of plastic foam, it preferably includes a gussetportion 20 between foot 18 and the upper surface of the bottom 16, forpurposes of rigidity. It is to be understood, however, that the size ofthe gusset is relatively immaterial, it serving the same function evenif it formed a solid fill-in between the foot 18 and the bottom 16,provided economics permits the additional material to be used. It isnoted that a plastic film cup (not shown) formed by the technique ofthis invention preferably does not include a similar gusset portion asfound in the foam cup.

Referring now more particularly to FIG. 5, the apparatus 22, for forminga container 10, basically includes a female die mold 24, a male die orplug body 26 and a trimmer and rim former 28, with the apparatus beingshown in its open state preliminary to forming a container. Associatedwith plug body 26 is a trapezoidal shaped insert member 30 having anupper periphery 32 substantially conforming to a portion of the bottomperiphery 34 of the plug body 26 but spaced therefrom to provide an airpassageway 36. Member 30 is held in this position by being secured tothe lower end of a shaft 38 threadably engaged through plug body 26which, in turn, is preferably slidably engaged at its upper end toformer 28.

Passageway 36 is connected with an internal passageway 40 within shaft38 through which a vacuum can be drawn or air introduced into the moldwhen desired. Other air passageways 48 can be employed from the side ofplug body 26 for providing better control in forming and/ or in removalof a formed container. Mold 24 can also be provided with air passageways43 and 45, the use of which is described hereinafter. The use ofpassageways 47 and 49 of former 28 are also later described.

Plug body 26 includes a peripheral leg 42 with its inside surfacesubstantially parallel to its outside surface. Leg 42 is formed of sucha length, from the inclined side of the plug body, that the outerperipheral edge 44 of the plug body has a diameter less than the innerperipheral corner 46 of the body.

Trimmer and rim former 28 is constructed so as to be slideable up anddown shaft 38, being controlled by a separate air cylinder than thatwhich controls plug body 26 (neither air cylinder being shown), andwhose internal hollow diameter X is just great enough so as to clear theoutside external periphery of plug body 26, but small enough to seatabout the upper portion of plug body 26 when engaged thereon. Whileformer 28 can also be fixed to shaft 38 at a spaced distance above plugbody 26 so that when the plug is fully lowered the former comes down theproper distance to perform simultaneously its bead forming function,later described, this has not been found preferable in practice althoughit is considered to be within the scope of the present invention.

Pocket 50 is provided within mold 24 about the periphery of the moldcavity for entry of projecting leg 52 of the former 28, the bottom ofthe leg 52 and the bottom of the pocket 50 being cooperatively andoppositely formed, reversely concave to one another, with radius curvedsurfaces 54 and 56. Outer edge 58 of leg 52 is formed sharp enough so asto cut through-a plastic sheet and act as a trimmer.

In forming container 10, preferably a sheet 60 of plastic foam is placedacross the top surface 62 of mold 24 and clamped (not shown) thereto,when plug 26 and former 28 are withdrawn therefrom. The sheet 60 engagestop surface 62 in a heated condition and as the hot plastic sheet isplugged and stretched into forming cavity 64 of mold 24, as shown inFIG. 6, or just prior thereto,

' a reverse vacuum can be drawn through passageways 36 and 40 to formraised bottom 16 thus providing the stacking feature of container 10.The exact timing of drawing the vacuum on the plug can be varied toobtain the desired sheet thickness of the raised bottom, that is, thefurther down the plug travels before a vacuum is drawn on the bottomwall, the thinner that wall will be. Thus, a desired bottom weight, onceformed, maintains its shape and thickness despite the further forming ofthe side wall 12 of container 10 as the plug continues to descend, asillustrated in FIG. 7, to the bottom position shown in dotted lines.Former 28 does not continue all the way down with plug body 26, butremains in an upper position until the step illustrated in FIG. 8,discussed hereinafter, is effected. Once the side wall 12 is formed, areverse vacuum can be drawn through passageway 45 whereby the foam onthe underside of the bottom 16 expands to form the gussets 20 and thebottom wall to any desired thickness since vacuum can be drawn on bothsides of the raised bottom 16.

Once the side wall 12 and bottom 16 are formed, trimmer and former 28descends, as shown in 'FIG. 8, shearing the upper periphery of the cupfrom sheet 60 with trimming edge 58 cutting against corner 66 of mold24. After the trimmer shears the container from sheet 60, the leg 52continues to descend, compressing the still heated foam betweencorresponding radiuses '54- and 56, to form bead-like lip 14. While aneffective bead can be formed from no more than the above describedaction, a head of a desired thickness and density can preferably beobtained by controlling a vacuum drawn through passageway 47 from curvedsurface 56, and thence out port 49, and a vacuum drawn on the reverseside of the bead-like lip 14 through passageway 43 from curved surface54, out through mold 24. The opposite pulling effect of the two vacuumsthus provides for a uniform cross-sectioned and full-shaped bead-likelip.

Thence the plug 26 and former 28 are withdrawn to the starting positionshown in FIG. 5 wherein the finished cup or container 10 is ejected.This ejection can be obtained by blowing air through passageways 36, 40and 48 of the plug body as it is being withdrawn from the mold cavity torelease the cup therefrom, which still remains in the mold, and thenblowing air into the mold cavity through passageways 43 and 45 to ejectthe cup. Another way to eject can be had by maintaining the vacuumthrough the plug body passageways 36, 40 and 48 while it is beingwithdrawn with the formed cup thereon, with air simultaneously beingblown into the mold cavity through passageways 43 and 45 if desired, andthen, when the plug body is fully withdrawn, releasing the vacuum andblowing air through passageways 36, 40 and 48 to release the cup fromthe plug body 26.

Accordingly, it can be seen that a well-controlled and formed cup body,including stacking features, a desired bottom weight, a controlledbead-like lip and a controlled wall thickness can be readily formed.While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in the art that various changes and modifications can be madetherein without departing from the spirit and scope of the invention.

I claim:

1. A frusto-conically shaped plastic foam container having a side wallextending between upper and lower peripheries, said side wall beinginclined inwardly from said upper periphery to said lower periphery,said lower periphery defining an integral generally recessed centerportion forming a bottom wall, a reinforcing gusset formed integrallywith and between said lower periphery and said bottom wall, said gussetbeing expanded to a substantially greater extent than the adjoiningportions of said side wall and bottom wall, the configuration of saidlower periphery 5 6 being essentially concentric with and smaller thanthe con- References Cited figuration of said bottom wall, whereby saidcontainer UNITED STATES PATENTS can be nested with another of identicalshape by the lower periphery of one resting upon the upper surface ofthe 2 816,697 12/ 1957 A b t m w ll of h h 5 3,059,810 10/1962 Edwards.

2. The container of claim 1 wherein said plastic foam is an expandedpolystyrene. GEORGE E. LOWRANCE, Primary Examiner.

